[Show abstract][Hide abstract] ABSTRACT: Phantom-limb pain (PLP) belongs among difficult-to-treat chronic pain syndromes. Treatment options for PLP are to a large degree implicated by the level of understanding the mechanisms and nature of PLP. Research and clinical findings acknowledge the neuropathic nature of PLP and also suggest that both peripheral as well as central mechanisms, including neuroplastic changes in central nervous system, can contribute to PLP. Neuroimaging studies in PLP have indicated a relation between PLP and the neuroplastic changes. Further, it has been shown that the pathological neuroplastic changes could be reverted, and there is a parallel between an improvement (reversal) of the neuroplastic changes in PLP and pain relief. These findings facilitated explorations of novel neuromodulatory treatment strategies, adding to the variety of treatment approaches in PLP. Overall, available treatment options in PLP include pharmacological treatment, supportive non-pharmacological non-invasive strategies (eg, neuromodulation using transcranial magnetic stimulation, visual feedback therapy, or motor imagery; peripheral transcutaneous electrical nerve stimulation, physical therapy, reflexology, or various psychotherapeutic approaches), and invasive treatment strategies (eg, surgical destructive procedures, nerve blocks, or invasive neuromodulation using deep brain stimulation, motor cortex stimulation, or spinal cord stimulation). Venues of further development in PLP management include a technological and methodological improvement of existing treatment methods, an implementation of new techniques and products, and a development of new treatment approaches.
Journal of Pain Research 03/2012; 5:39-49. DOI:10.2147/JPR.S16733
[Show abstract][Hide abstract] ABSTRACT: Reliable imaging of eloquent tumour-adjacent brain areas is necessary for planning function-preserving neurosurgery. This study evaluates the potential diagnostic benefits of presurgical functional magnetic resonance imaging (fMRI) in comparison to a detailed analysis of morphological MRI data.
Standardised preoperative functional and structural neuroimaging was performed on 77 patients with rolandic mass lesions at 1.5 Tesla. The central region of both hemispheres was allocated using six morphological and three functional landmarks.
fMRI enabled localisation of the motor hand area in 76/77 patients, which was significantly superior to analysis of structural MRI (confident localisation of motor hand area in 66/77 patients; p < 0.002). FMRI provided additional diagnostic information in 96% (tongue representation) and 97% (foot representation) of patients. FMRI-based presurgical risk assessment correlated in 88% with a positive postoperative clinical outcome.
Routine presurgical FMRI allows for superior assessment of the spatial relationship between brain tumour and motor cortex compared with a very detailed analysis of structural 3D MRI, thus significantly facilitating the preoperative risk-benefit assessment and function-preserving surgery. The additional imaging time seems justified. FMRI has the potential to reduce postoperative morbidity and therefore hospitalisation time.
European Radiology 07/2011; 21(7):1517-25. DOI:10.1007/s00330-011-2067-9 · 4.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Perfusion computed tomography (PCT) allows to quantitatively assess haemodynamic characteristics of brain tissue. We investigated if different brain tumor types can be distinguished from each other using Patlak analysis of PCT data.
PCT data from 43 patients with brain tumours were analysed with a commercial implementation of the Patlak method. Four patients had low-grade glioma (WHO II), 31 patients had glioblastoma (WHO IV) and eight patients had intracerebral lymphoma. Tumour regions of interest (ROIs) were drawn in a morphological image and automatically transferred to maps of cerebral blood flow (CBF), cerebral blood volume (CBV) and permeability (K (Trans)). Mean values were calculated, group differences were tested using Wilcoxon and Mann Whitney U-tests.
In comparison with normal parenchyma, low-grade gliomas showed no significant difference of perfusion parameters (p > 0.05) , whereas high-grade gliomas demonstrated significantly higher values (p < 0.0001 for K (Trans), p < 0.0001 for CBV and p = 0.0002 for CBF). Lymphomas displayed significantly increased mean K(Trans) values compared with unaffected cerebral parenchyma (p = 0.0078) but no elevation of CBV. High-grade gliomas show significant higher CBV values than lymphomas (p = 0.0078).
PCT allows to reliably classify gliomas and lymphomas based on quantitative measurements of CBV and K (Trans).
European Radiology 05/2010; 20(10):2482-90. DOI:10.1007/s00330-010-1817-4 · 4.01 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Trigeminal neuralgia (TN) is a pain state characterized by intermittent unilateral pain attacks in one or several facial areas innervated by the trigeminal nerve. The somatosensory cortex is heavily involved in the perception of sensory features of pain, but it is also the primary target for thalamic input of nonpainful somatosensory information. Thus, pain and somatosensory processing are accomplished in overlapping cortical structures raising the question whether pain states are associated with alteration of somatosensory function itself. To test this hypothesis, we used functional magnetic resonance imaging to assess activation of primary (SI) and secondary (SII) somatosensory cortices upon nonpainful tactile stimulation of lips and fingers in 18 patients with TN and 10 patients with TN relieved from pain after successful neurosurgical intervention in comparison with 13 healthy subjects. We found that SI and SII activations in patients did neither depend on the affected side of TN nor differ between operated and nonoperated patients. However, SI and SII activations, but not thalamic activations, were significantly reduced in patients as compared to controls. These differences were most prominent for finger stimulation, an area not associated with TN. For lip stimulation SI and SII activations were reduced in patients with TN on the contra- but not on the ipsilateral side to the stimulus. These findings suggest a general reduction of SI and SII processing in patients with TN, indicating a long-term modulation of somatosensory function and pointing to an attempt of cortical adaptation to potentially painful stimuli.
Human Brain Mapping 11/2009; 30(11):3495-508. DOI:10.1002/hbm.20773 · 5.97 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Obwohl neurodestruktive Verfahren sehr effektiv in der Behandlung von Schmerzen malignen und nichtmalignen Ursprungs sein
können, werden sie heute kaum noch durchgeführt. Dies liegt zum einen daran, dass sie in der Vergangenheit mit einer hohen
Komplikationsrate verbunden waren. Diese Komplikationen beinhalteten das Auftreten neuer neurologischer Defizite und – bei
entsprechend langer Nachbeobachtungszeit – das Wiederauftreten der früheren Schmerzen oder neuer Schmerzen durch eine Deafferentierung.
Zum anderen gelingt es, mit weniger invasiven, z.B. neuromodulatorischen oder nichtinvasiven Verfahren (systemische, orale,
transdermale Opioide, Koanalgetika) einen großen Teil dieser Schmerzen befriedigend zu reduzieren. Dennoch bestehen auch heute
noch bestimmte, sehr eingeschränkte Indikationen für die Durchführung neurodestruktiver Verfahren.
Although surgical ablative procedures can be effective in the management of chronic pain of malignant and non-malignant origin,
they are often disregarded as treatment options due to the fact that in the past these procedures were associated with high
complication rates. The complications include the development of new neurological deficits and in cases of long-term follow-up,
the occurrence of the old or new pain syndromes by deafferentation. On the other hand there exist many less invasive, e.g.
neuromodulatory procedures or non-invasive measures (systemic oral or transdermal opioids) which are able to considerably
reduce chronic pain. Nevertheless, there remain certain very restricted indications for the use of neuroablative procedures
for the treatment of chronic pain even today.
Der Schmerz 10/2009; 23(5):531-543. DOI:10.1007/s00482-009-0833-2 · 1.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although surgical ablative procedures can be effective in the management of chronic pain of malignant and non-malignant origin, they are often disregarded as treatment options due to the fact that in the past these procedures were associated with high complication rates. The complications include the development of new neurological deficits and in cases of long-term follow-up, the occurrence of the old or new pain syndromes by deafferentation. On the other hand there exist many less invasive, e.g. neuromodulatory procedures or non-invasive measures (systemic oral or transdermal opioids) which are able to considerably reduce chronic pain. Nevertheless, there remain certain very restricted indications for the use of neuroablative procedures for the treatment of chronic pain even today.
Der Schmerz 09/2009; 23(5):531-41; quiz 542-3. · 1.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Several lines of evidence point to a disturbance of olivo-cerebellar pathways in essential tremor (ET). For example, subjects with ET exhibit deficits in eyeblink conditioning, a form of associative learning which is known to depend on the integrity of olivo-cerebellar circuits. Deep brain stimulation (DBS) of the ventrolateral thalamus is an established therapy for ET. If tremor in ET is related to the same pathology of the olivo-cerebellar system as impaired eyeblink conditioning, one may expect modulation of eyeblink conditioning by DBS. Delay eyeblink conditioning was assessed in 11 ET subjects treated with DBS (ET-DBS subjects) who were studied on two consecutive days with DBS switched off (day 1) and on (day 2). For comparison, 11 age-matched ET subjects without DBS (ET subjects) and 11 age-matched healthy controls were studied. On day 1, eyeblink conditioning was diminished in ET-DBS subjects and in ET subjects compared with controls. When DBS was switched on ET-DBS subjects exhibited conditioning rates within the range of controls on day 2, while ET subjects improved only minimally. Improved eyeblink conditioning in ET-DBS subjects suggests that thalamic DBS counteracts a functional disturbance of olivo-cerebellar circuits which is thought to be responsible for eyeblink conditioning deficits in ET. Modulation of cerebello-thalamic and/or thalamo-cortico-cerebellar pathways by DBS may play a role.
[Show abstract][Hide abstract] ABSTRACT: Deep brain stimulation (DBS) of the posterior hypothalamic area is a new treatment option for patients with refractory chronic cluster headache (CCH). A review of the literature reveals that studies based on large numbers of patients, long-term observations and controlled randomised trials are still lacking. In 2006 a case report of the first patient in Germany to be operated on to allow DBS was published, and we now present a report of this patient's course in the first 6 months after the operation; in addition, a current literature review is discussed. In July 2005 a DBS lead was placed in the left posterior hypothalamic area of this 39-year-old woman with CCH. Stimulation on demand achieved complete suppression of the cluster attacks, and the patient no longer needed medication. After about 8 months a decreasing effect of the stimulation, with only about 50% reduction of cluster attacks, and stimulation-induced side effects were observed. Neither reprogramming of the stimulation parameters nor pharmacological therapy with on-demand and long-term medication reduced the frequency or severity of CCH attacks to the level experienced in the early postoperative stage. Because of intolerable subjective side effects and tension-related pain at the site of the connection cable, in September 2006 the whole system was explanted at the patient's request.DBS in the posterior hypothalamic area is an invasive treatment option for use in cases with CCH that is refractory to any pharmacological therapy. As demonstrated by this case report, it is not possible to give a prognosis concerning its long-term efficacy: despite the initial excellent benefit there can be a reduction and even a loss of the effect of stimulation. The clinical results and long-term follow-up observations of the few cases published so far need to be evaluated in a larger multicentre trial with a double-blind study design.
[Show abstract][Hide abstract] ABSTRACT: To prospectively assess the feasibility of standardized presurgical functional magnetic resonance (MR) imaging for localizing the Broca and Wernicke areas and for lateralizing language function.
The study was approved by the responsible ethics commission, and patients gave written informed consent. Eighty-one patients (36 female and 45 male patients; age range, 7-75 years) with different brain tumors underwent blood oxygen level-dependent functional MR imaging at 1.5 T with two paradigms: sentence generation (SG) and word generation (WG). Functional MR imaging measurements, data processing, and evaluation were fully standardized by using dedicated software. Four regions of interest were evaluated in each patient: the Broca and Wernicke areas and their anatomic homologues in the right hemisphere. Statistics were calculated.
The SG and WG paradigms were successfully completed by all (100%) and 70 (86%) patients, respectively. Success rates in localizing and lateralizing language were 96% for the Broca and Wernicke areas with the SG paradigm, 81% for the Broca area and 80% for the Wernicke area with the WG paradigm, and 98% for both areas when the SG and WG paradigms were used in combination. Functional localizations were consistent for SG and WG paradigms in the inferior frontal gyrus (Broca area) and the superior temporal, supramarginal, and angular gyri (Wernicke area). Surgery was not performed in seven patients (9%) and was modified in two patients (2%) because of functional MR imaging findings.
Functional MR imaging proved to be feasible during routine diagnostic neuroimaging for localizing and lateralizing language function preoperatively.
[Show abstract][Hide abstract] ABSTRACT: Most so-called idiopathic trigeminal neuralgias (TN) are caused by neurovascular compression. Does the size of the cerebellopontine cistern play a role in favoring a neurovascular conflict? The aim of this prospective study was to measure the volume of the parapontine cistern in patients with idiopathic TN and to perform a comparison with healthy controls.
In 25 patients with unilateral idiopathic TN and 17 healthy participants, high-resolution 1.5-T magnetic resonance imaging scans of the parapontine region and the trigeminal nerve were performed. A coronal T2-weighted, true fast imaging steady-state precession sequence with a slice thickness of 0.9 mm was used to define the surrounding cerebrospinal fluid space from the trigeminal root entry zone to Meckel's cave. The volume of the pontomesencephalic cistern was calculated using a standardized method.
The mean difference of the volume of the affected and opposite side was 13% in patients with TN. In all patients, a significantly smaller volume of the cistern was found on the affected side (P < 0.01). Healthy controls showed a mean volumetric side difference of 9%, which was not significant (P > 0.05).
High-resolution magnetic resonance imaging scans are able to demonstrate significant volumetric differences of the pontomesencephalic cistern in patients with unilateral TN. A smaller cistern may be correlated with the occurrence of a neurovascular compression, and these findings support the neurovascular compression theory in idiopathic TN.
[Show abstract][Hide abstract] ABSTRACT: Objectives. Spinal cord stimulation (SCS) is an effective treatment option for chronic radicular neuropathic pain syndromes. This prospective study was performed to examine the peripheral effects of SCS on sensation using quantitative sensory testing (QST). Materials and Methods. We measured two consecutive QST measurements for thermal, tactile-static, tactile-dynamic, vibratory, and pain sensation of the lower limbs in seven patients with chronic unilateral radicular neuropathic pain who underwent SCS implantation for their pain. Measurements were performed when SCS was turned off and once again during SCS and subsequent reduced pain levels. Results. Baseline QST demonstrated significantly increased thresholds for tactile and warm and cold detection in the pain area. With SCS active, a significant reduction of the cold and warm perception and mechanical detection thresholds was found on the painful side (p < 0.01). Although not significant (p > 0.01), altered sensory thresholds with active SCS also were found at the healthy side where no paresthesias were felt. Conclusion. SCS leads to bilateral subclinical effects even if the evoked paresthesias are only unilateral. Pain perception thresholds are not altered with therapeutic SCS.
[Show abstract][Hide abstract] ABSTRACT: Chronic subthreshold stimulation of the contralateral precentral gyrus is used in patients with intractable neuropathic pain for more than 15 years. The aim of this study was to analyse retrospectively our own patient group with long term follow-up of 10 years. Seventeen patients with chronic neuropathic pain were treated with contralateral epidural stimulation electrodes. In 10 cases, trigeminal neuropathic pain (TNP) and in seven cases post-stroke pain (PSP) were diagnosed. The placement of the electrodes was performed in local anaesthesia using neuronavigation and intraoperative neuromonitoring. A test trial of minimum one week including double-blind testing was conducted and pain intensity was measured using a visual analogue scale (VAS). Correct placement of the electrode was achieved in all patients using intraoperative neurophysiological monitoring. Double-blind testing was able to identify 6 (35%) non-responders. In 5 of 10 (50%) with TNP and 3 of 7 (43%) with PSP a positive effect with pain reduction > or = 50% was observed. The mean follow-up period was 3.6 years (range 1-10 years) and includes a patient with 10 years of positive stimulation effect. Stimulation of the motor cortex is a treatment option for patients with chronic neuropathic pain localized in the face or upper extremity. Double-blind testing can identify non-responders. Patients with TNP profit more than patients with PSP. The positive effect can last for ten years in long-term follow-up.
[Show abstract][Hide abstract] ABSTRACT: Electrical intracerebral stimulation (also referred to as deep brain stimulation [DBS]) is a tool for the treatment of chronic pain states that do not respond to less invasive or conservative treatment options. Careful patient selection, accurate target localization, and identification with intraoperative neurophysiological techniques and blinded test evaluation are the key requirements for success and good long-term results. The authors present their experience with DBS for the treatment of various chronic pain syndromes.
In this study 56 patients with different forms of neuropathic and mixed nociceptive/neuropathic pain syndromes were treated with DBS according to a rigorous protocol. The postoperative follow-up duration ranged from 1 to 8 years, with a mean of 3.5 years. Electrodes were implanted in the somatosensory thalamus and the periventricular gray region. Before implantation of the stimulation device, a double-blinded evaluation was carefully performed to test the effect of each electrode on its own as well as combined stimulation with different parameter settings. The best long-term results were attained in patients with chronic low-back and leg pain, for example, in so-called failed-back surgery syndrome. Patients with neuropathic pain of peripheral origin (such as complex regional pain syndrome Type II) also responded well to DBS. Disappointing results were documented in patients with central pain syndromes, such as pain due to spinal cord injury and poststroke pain. Possible reasons for the therapeutic failures are discussed; these include central reorganization and neuroplastic changes of the pain-transmitting pathways and pain modulation centers after brain and spinal cord lesions.
The authors found that, in carefully selected patients with chronic pain syndromes, DBS can be helpful and can add to the quality of life.
[Show abstract][Hide abstract] ABSTRACT: Spinal cord stimulation (SCS) is an effective alternative treatment in patients with chronic neuropathic pain and mainly radicular distribution. The aim of this prospective study was to investigate changes in BOLD signal with fMRI during active SCS and to correlate the results with the clinical pain intensity, measured with a visual analogue scale (VAS).
Three patients with failed back surgery syndrome were tested during the clinical trial of SCS. A first fMRI was performed with marked pain and a high VAS score. Before the second fMRI a therapeutic stimulation phase with pain reduction was carried out.
With high pain levels SCS activated the cingulate gyrus, thalamus, prefrontal cortex, supplementary motor area and postcentral gyrus. After pain reduction, SCS did not elicit these activations in the second fMRI, using the same stimulation parameters.
In patients with chronic neuropathic pain and high VAS levels, SCS elicited BOLD activation in the cingulate gyrus, thalamus, prefrontal cortex, and primary and secondary somatosensory area. Pain reduction by SCS resulted in a reduction of functional activity in these areas as revealed by follow-up fMRI.
Der Schmerz 12/2005; 19(6):497-500, 502-5. · 1.02 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Hintergrund
Die epidurale Rückenmarkstimulation („spinal cord stimulation“, SCS) stellt bei chronischen neuropathischen Schmerzsyndromen mit radikulären Schmerzen eine effektive Behandlungsalternative dar. Ziel dieser prospektiven Studie war es, den Effekt der SCS auf die Hirnaktivierung in schmerzassoziierten Arealen mit der fMRT zu untersuchen und die Veränderungen mit der subjektiven Schmerzwahrnehmung (VAS) zu korrelieren.
Material und Methoden
Drei Patienten mit lumbalem Postnukleotomiesyndrom wurden im Rahmen der klinischen Testphase der SCS untersucht. Die 1. fMRT-Messung erfolgte bei deutlichem Schmerzempfinden des Patienten. Vor der 2. Messung wurde eine therapeutische Stimulationsphase mit Schmerzreduktion durchgeführt.
Bei vorhandenen Schmerzen zeigte sich unter SCS eine Aktivierung im Bereich des Gyrus cinguli, Thalamus, präfrontalen Kortex, Supplement-motorischen Areals sowie im Gyrus postcentralis. Nach wirksamer Stimulation und Schmerzreduktion konnte im 2. fMRT unter identischen Stimulationsparametern diese Aktivierung nicht mehr nachgewiesen werden.
Bei Patienten mit chronisch neuropathischen Schmerzen konnten unter SCS Hirnaktivierungen im Gyrus cinguli, Thalamus, Insel, präfrontalen Kortex und im primären und sekundären somatosensiblen Kortex im fMRT dargestellt werden. Eine Schmerzreduktion durch die SCS geht mit einer reduzierten funktionellen Aktivierung in schmerzassoziierten Zentren einher.
Der Schmerz 12/2005; 19(6):497-505. DOI:10.1007/s00482-005-0388-9 · 1.02 Impact Factor